A: Tom, why did you turn tail when you saw me after school?
B: I'm sorry, mum. I just wanted...
A : Wwhat?
B: I just wanted to play and i did not want to do my homework early.
exp. To run away or flee, usually in fear.（躲开，逃跑，掉头拔腿就跑）
The burglars turned tail at the sound of our security alarm.
e.g. I couldn't just turn tail and run but I wasn't going to fight that monster, either.
e.g. Sometimes turning tail is the only sensible thing to do.